The purpose of this research is to investigate the relationship between children's play activities and sex-typed behaviors. It is proposed that young children's play activities differ in the amount of structure provided to the participating child. Structure is defined as the degree to which there are externally imposed rules or guidelines about appropriate behavior; these can be provided through modeling or through direct instruction and feedback by adults. Activities differing in structure are thought to cultivate different behavioral skills. Low structure activities promote "creating one's own structure" through behavior such as independence, initiative, leadership; high structure activities may promote compliance and dependence on "fitting into structures created by others". Differential exposure to high and low structure activities is proposed as one antecedent for sex differences in behavior. It is expected that boys gravitate to low structure activities and girls to high structure activities. Therefore, boys have more opportunity to learn to create structure; girls have more practice in compliance and other behaviors indicating fitting into structures created by others. Data from the first study, a correlational study based on naturalistic observations in preschool classrooms, support these hypotheses. In the second study, structure level was experimentally manipulated. Data from this study are being analysed. The final study, scheduled for September, 1980, will use the level of classroom activity structure as an intervention technique for treatment of children displaying extreme sex-typed behaviors.